some oai- notebooks contain AzureOAI import and calls: rewrite to OAI calls

[bmerkle]

Describe the bug

some for the oai-notebooks (contain AzureOAI import and method calls
We should rewrite oai-notebooks and python file to only include OpenAI imports and method calls

example:
https://github.com/microsoft/generative-ai-for-beginners/tree/main/06-text-generation-apps/python/oai-assigment.ipynb

we should also use dotenv in a consistent way

[github-actions]

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